Recently ultrasound diagnosis and therapy have become widely used, and many surgical procedures have been replaced by gentler and less time consuming invasive needle therapy to the benefit of the patient. Inter alia, ultrasonic imaging of maternal and fetal tissues has greatly facilitated prenatal diagnosis and treatment, and ultrasound imaging devices greatly assist the physician in properly positioning a biopsy needle to perform amniocentesis, cordocentesis and trans-abdominal chorionic sampling.
There are many different biopsy techniques and needles, and the needle depends on the type of patient and the target organ. The method most widely used today is the "free hand" technique, whereby the transducer is placed at a certain distance from the entry site of the needle and the needle is manipulated with one hand. This technique requires considerable skill and frequently repeated punctures, unless the target is relatively large or located superficially. For these reasons and because manipulation of the needle as guided by an ultrasound image generally requires both hands of the physician, much effort has been made to design and provide automatic devices for guiding the needle as directed by the ultrasound beam.
Early developed devices include a needle attached to an ultrasound transducer housing, the needle being spaced from and articulated with respect to the transducer. Such devices help the physician to manually direct the needle onto the desired biopsy location and to insert it to the required depth. Such devices are, for instance, described in U.S. Pat. No. 4,899,756, issued to Sonec, and U.S. Pat. No. 4,911,173, issued to Terwillinger. While all of these devices provided some movement of the needle guide and needle relative to the transducer, the physician is nevertheless significantly hampered in positioning the needle prior to and during insertion, as well as in re-positioning the transducer once the needle is inserted into the body.
Other commonly used devices include a transducer and a coaxial needle guide for manually positioning and inserting a needle. While these devices allow rapid and convenient guided biopsy, they have several significant drawbacks: 1) The transducer must be placed directly over the lesion, thereby requiring its sterilization or its draping by a sterile covering. 2) The physician is forced to hold the transducer in one hand while using the other for sterilizing and anesthetizing the biopsy site. 3) After inserting the needle, the transducer must be held by an assistant or must be removed while the needle is maneuvered. 4) Multiple passes may necessitate re-positioning of the transducer and re-insertion of the needle. 5) The existing needle guides may make it difficult to enter some superficial lesions. 6) Most transducers are flat, straight and relatively large, making some costal and subcostal approaches difficult.
A completely automatic apparatus for computer controlled stereotactic brain surgery is described in U.S. Pat. No. 5,078,140, issued to Kwoh. This apparatus suffers from the drawback that the needle or needle guide is integrally connected to the apparatus, thereby not permitting the physician to choose the most suitable trajectory of the needle towards the target. In addition, the apparatus is highly complicated, expensive and has to be calibrated for every operation.
Another device is an ultrasound directed needle guide, developed by the present Applicant, and disclosed in Israel Patent Application 107,523. It includes an ultrasound transducer and a needle, guide which holds a syringe and needle. Both the transducer and the needle guide are each attached to a universally movable arm such that each may be placed on a patient's body in any desired position. The arms are vertically movable along a vertical post and are provided with direction sensors configured to signal the position of the attached instruments to computer means. The transducer transmits the image of the target to an imaging device which in turn transmits the information to the computer means which is programmed to indicate the angular direction of the needle guide onto the target and to direct the physician to place the needle in the correct position and direction on the patient's body.